I have a 1980 300sd with a failed AC and Heating system.

A week or two ago, I posted a question about identifying the proper servo unit in the junk yard and received very helpful responses.

So far, I have not made it to the junk yard but am going this week or next. Last night, the thought occured to me that maybe after finding one (if I am lucky), it might not solve my problem.

Would someone here describe the functions of a servo and the effects of a failed servo?

Also, what model and year of cars might have the newer aluminum bodied unit?

Thanks

__________________
DCM

1977 240d
1980 300sd
1987 Chevrolet Suburban

It looks like I got responses to that other posting which I cannot find right now. The cost of rebuilding or replacing mine appears to be in the $650-$700 range.

The car would be worth it if that was all it took to fix the A/C and heating problems. The car is in excellent shape, even with 216,000 miles on it.

An operating used Servo would be better if I could find one and if it was really in good operating condition.

It looks like the servo is the most critical element in the system and the only other parts that might possible need work would be the heater core if the Servo did not fix it.

Thanks for the responses.

__________________
DCM

1977 240d
1980 300sd
1987 Chevrolet Suburban